External Vs Submersible Pump?

posted in: Blog

Most rainwater tanks will require a pump to deliver enough pressure to send the water where it needs to go. This is particularly the case when the rainwater tank is used to pump water to toilets, washing machines & garden taps.

There are two types of pumps to choose from - external pumps or submersible pumps.

External Pumps

External pumps (aboveground or surface mounted pump) are the most common type of rainwater pump. As the name suggests, they are usually installed beside the tank or somewhere close by. It is a common misconception that external water pumps are waterproof. They are not, so need to be protected from the elements. A pump cover should be used if the pump is going to be exposed to the weather.

Submersible Pumps

Submersible pumps are installed inside the water tank. The attached pipework is installed through the top of the tank & pumped out from here.

What are the advantages & disadvantages of each?

  • Price point - Submersible pumps are generally more expensive than external pumps. The fact that they have to be made watertight and sealed makes them more labour intensive to manufacture.

Submersible pumps are generally also more expensive to service. There are also a lot of submersible pumps on the market that are deemed to be a throw-away item due to the cost of repair.

  • Noise - Without a doubt, submersible pumps win hands down when it comes to noise. External pumps can be noisy, some more then others. Interestingly, even pumps of the same model can have differing levels of noise. Pump covers will absorb some of the noise, but not enough to match the quieter levels of the submersible pump range.

The exception is the DAB E.SYBOX external pressure system which prides itself on its quiet operation.

  • Serviceability - As service & repair agents, we can confirm that the external pumps are easier to service & to repair. As submersible pumps are located inside your water tank, a ladder is generally required to reach the access point. There is more labour required to remove a submersible pump & there is also the question as to whether the pump can actually be repaired. An example would be a blown capacitor which is essentially the starter motor for your pump. For an external pump, it is relatively easy to locate & replace a capacitor & it is not an expensive repair. For a submersible pump on the other hand, the repair could be costly.
  • Location- If available space near your rainwater tank is at a premium, a submersible pump would be a better option. It is worth noting though that you must have enough head-room to be able to get the pump in and out of the tank. This is particularly the case when the rainwater tank is installed under the eaves or under a deck.

There are other factors to consider including energy efficiency, how many taps you are connecting to and how far away your pump is located. If you would like to way up your options regarding the right pump for you, contact us on 98243733